1. Field of the Invention
The present invention relates to a waste toner collecting device for collecting residual toner remaining on the surface of an image carrier or an intermediate transfer body. The present invention also relates to an image forming apparatus incorporating this waste toner collecting device.
2. Description of Related Art
In electrophotographic image forming apparatuses, image transfer methods have been widely used in which a photoconductive drum serving as an image carrier and a transfer roller serving as a transfer member come in contact with or come close to each other to form a transfer region, paper is passed through the transfer region, and a toner image formed on the surface of the photoconductive drum is transferred onto the paper. With such transfer methods, a small amount of toner may remain on the surface of the photoconductive drum without being transferred to the paper. The residual toner remaining on the surface of the photoconductive drum needs to be cleaned off by a cleaning unit; otherwise, it may hinder the next image formation.
In an image forming apparatus in which a toner image formed on the surface of a photoconductive drum is primarily transferred to the surface of an intermediate transfer body, and then the toner image that has been transferred to the surface of the intermediate transfer body is secondary transferred to paper, a small amount of toner may also remain on the surface of the intermediate transfer body without being transferred to the paper. The residual toner remaining on the surface of the intermediate transfer body also needs to be removed by a cleaning unit.
Waste toner collected by a cleaning unit is transported through a pipe by use of a transport member such as a screw, and is collected by a waste toner collecting device. The waste toner collecting device is provided with a waste toner collecting container which receives and accommodates waste toner and a waste toner transport mechanism for transporting waste toner to the waste toner collecting container. The waste toner collecting container is typically formed of synthetic resin such as ABS resin. As a result, it is disadvantageously difficult to place the waste toner collecting container in a small space, or to have waste toner uniformly distributed to every corner of the waste toner collecting container.
One example of waste toner collecting devices proposed to deal with the above disadvantages is disclosed in JP-A-H10-161501. The waste toner collecting device is provided with an inflatable collecting bag as a waste toner collecting container.
Being provided with the inflatable collecting bag that can be inflated in a small space to make the most of the small space, this conventional waste toner collecting device can collect a larger amount of waste toner. Typically, however, in conventional waste toner collecting devices including this one, waste toner freely falls down from above into a collecting bag or a collecting container, the waste toner is liable to accumulate in and around the area under a toner inlet. In particular, in the case where the above-mentioned inflatable collecting bag is used, a toner flow path in the vicinity of the toner inlet may become narrower as a result of insufficient initial inflation of the collecting bag or change in the shape of the bag occurring as more waste toner is collected therein.
If waste toner keeps accumulating in the vicinity of the toner inlet as described above, the toner inlet soon becomes inconveniently clogged up with waste toner even when enough space is left for more waste toner at the rear portion inside the collecting bag. As a result, the waste toner collecting device needs to be replaced at an inconveniently high rate, and this may results in very high running cost, and there may arise a problem of waste toner overflowing from the toner inlet.
Also, the above described waste toner collecting device, in which waste toner is allowed to fall down freely from above into the waste toner collecting bag, needs to be structured such that the collecting bag extends below the waste toner transport mechanism. Therefore, in positioning the waste toner collecting device, sufficient space for allowing waste toner to fall down and for accommodating more waste toner needs to be secured in the vertical direction. This may limit, in terms of design, the overall structure of the waste toner collecting device and the internal structure of the image forming apparatus incorporating the toner collecting device.